The moisture from the apple mysteriously stops the edges of the baking from going stale and she gets a good few days extra out of every batch of baking.

In the name of investigative journalism I have tried hard to research this magical phenomenon, to discover WHY an apple could possibly hold such power but it appears to be a mystery too deep (for the front page of Google) to fathom.

However, my faith in the knowledge and wisdom of a granny, when it comes to baking defies all need for a logical answer.

What is your favourite thrifty folk-knowledge tip that has no reason but definitely works?